Electrical device contactor

ABSTRACT

A contact leaf bank for an electrical contactor preferably etched from a single uniform sheet of resiliently flexible, electrically conductive material comprises a ground sheet defining a plurality of uniformly-spaced, elongated, parallel slots in which are singularly disposed a plurality of resiliently flexible, elongated leaves each having and end portion adapted to be a contact finger, the tip of each contact finger preferably being rhodium-plated for hardness. A pair of spaced and opposing contact leaf banks are two elements of a contact assembly which futher comprises a base member in which a base end of each contact leaf bank is anchored, a device rail which in one form is a single track upon which an electrical device rides is centrally interposed between the contact leaf banks, the device rail being adapted to seat a device such that side leads of the device are aligned with the contact fingers and the spacing of the contact banks being such that the banks can be bent inboardly to make wiping contact between the device leads and the contact fingers, a pair of rockers one affixed to each bank at an end opposite the bank&#39;s anchored end and adapted to be reciprocatingly rocked or rotated toward and away from the device rail by an over-travel compensated actuating mechanism, the portion of each contact leaf bank between its respective rocket and the base member acting as a resilient hinge, and connector adaptors housed in the base member for providing electrical communication between the contact fingers and connectors also housed in the base member.

This is a division of application Ser. No. 942,244, filed Dec. 16, 1986,now U.S. Pat. No. 4,836,797.

BACKGROUND OF THE INVENTION

This invention relates in general to electrical contactors used to maketemporary contact with the leads of electrical devices, especially fortesting purposes.

Prior art contactors consist of a plurality of individually manufacturedand individually assembled contact leaves with no means of controllingthe electrical characteristic impedance of the leaves, so that, inaddition to being very costly to manufacture, the contactors createimpedance anomalies between the test electronics and a device undertest. Such anomalies tend to cause signal reflections which deterioratethe rise and fall times of test signals. Heretofore this has beenacceptable for most devices because the deterioration was withinacceptable limits due to the relatively slow rise and fall times, andtherefore low frequency of the major components present in the the testsignals. But there is now an urgent need for a high frequency contactor,one whose characteristic impedance substantially matches that of thetransmission medium between the contactor and the test electronics sothat the faster rise and fall times of higher frequency test signals canbe passed through a contactor substantially unaffected by the contactor.By maintaining the integrity of the rise and fall times of the signals,accurate testing of high speed devices is made possible.

A contactor without high frequency capability, however, would addartifacts to the signal, which mimic the characteristics of a defectivedevice, therefore resulting in costly rejection of good devices.

Other advantages and attributes of this invention will be readilydiscernible from a reading of the text hereinafter.

SUMMARY OF THE INVENTION

This invention presents a contact leaf bank for an electrical contactorcomprising a uniform sheet of resiliently flexible, electricallyconductive material, a plurality of elongated strips of resilientlyflexible, electrically conductive material, a corresponding plurality ofelongated, parallel slots defined by the sheet in which the strips arecentrally disposed, one strip for each slot, a portion of the stripsbeing generally coplanar with the sheet and corresponding end portions(herein called contact fingers) of the strips being divergent from theplane of the sheet, and means securing the strips and the sheet inrelation to each other. Preferably the sheet and strips are photo-etchedfrom a single sheet of a copper-nickel or copper-berylium alloy, and thestrips (herein called contact leaves) are secured in the slots bylaminations. A contact assembly comprises a pair of spaced contact leafbanks, a base member in which a base end of each contact leaf bank isanchored, such that the contact fingers of one bank faces the contactfingers of the other bank, a device rail interposed between the banksand adapted to seat an electrical device such that the side exitingleads of the device are aligned with the contact fingers, a rocker meansaffixed to each bank at an end opposite to the anchored bank end andadapted to be rotated toward and away from the device rail by anover-travel compensated actuating mechanism, the respective contact leafbank of each rocker means acting as a hinge, adaptor means housed in thebase plate by which the contact leaves are in electrical communicationwith connectors preferably also housed in the base plate.

An object of this invention is to provide a device contactor with auniform and controlled characteristic impedance.

A further object of this invention is to provide a device contactor witha characteristic impedance which substantially matches the impedance ofthe transmission medium between the test electronics and the contactor.

A further object of this invention is to provide a device contactor witha characteristic impedance which substantially matches thecharacteristic impedance of a coaxial cable.

A further object of this invention is to permit connection of powersupply filter capacitors to the device via short leads having lowimpedance.

A further object is to permit easy fabrication and replacement of amultitude of small contacts by cutting them photochemically as a set,and securing them in relation to each other by laminating.

A further object of this invention is to fabricate a contact assemblywhich serves the dual purpose of flexible contacts as well as forming amulti-conductor controlled impedance transmission line, thus reducingparts count and assembly time, and therefore cost.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a contact leaf bank.

FIG. 2 is a perspective view of a reverse side of the contact leaf bankof FIG. 1.

FIG. 3 is a partial sectional view of the contact leaf bank of FIGS. 1and 2.

FIG. 4 is a plan view of a partially unfinished and unformed contactleaf bank.

FIG. 5 is a section of a finished and formed contact leaf bank takenalong a line colinear with a longitudinal axis of a contact leaf.

FIG. 6 is a front view of a rocker bar and a portion of some componentcells disposed therein.

FIG. 7 is a sectional view of the rocker bar taken along line 7--7 ofFIG. 6.

FIG. 8 is an end view of the rocker bar of FIG. 6.

FIG. 9 is a bottom view of an unformed connector adaptor.

FIG. 10 is a top view of the unformed connector adaptor.

FIG. 11 is a short edge view of a formed connector adaptor.

FIG. 12 is a partial plan view of an unlaminated connector adaptor.

FIG. 13 is a perspective view of a contactor drive mechanism.

FIG. 14 is a perspective view of a top side of a contactor bridge.

FIG. 15 is a perspective view of a bottom side of the bridge.

FIG. 16 is a plan view of the bridge with a cover removed.

FIG. 17 is a partial section of a conventional contactor.

FIG. 18 is a side view of a conventional contact finger.

FIG. 19 is a front view of the conventional contact finger.

DESCRIPTION OF PREFERRED EMBODIMENT

Referring to FIGS. 1, 2 and 3, a contact assembly, generally designated2 is shown to have a base plate 4 with an integral and centrallydisposed raised portion 6. The base 4 is formed by a central base piece8 being joined edgewise with and between two outer base pieces, 10 and12, by means a plurality of recessed socket head bolts 14. Projectingnormally from the raised portion 6 are a pair of spaced guide pins, 16and 18, which engage matching guide holes in printed circuit board 30.The raised portion 6 defines a plurality of cavities 22 in which arehoused a pluralilty of coaxial connectors 20. The coaxial connectors 20are preferably miniature high frequency connectors or the like with eachconnector having a plurality of solderable ground leads 24 and a signallead 26 projecting from one end of a barrel housing, the other end beingadapted to couple with a mating coaxial connector 28 typically mountedon a printed circuit board 30 which comprises or interfaces to devicetest electronics. A plurality of connector apertures 32 defined by theraised portion 6 of the base plate 4 expose a mating end of the housedconnectors 20 to permit said coupling. The outer base pieces 10 and 12each define a cavity 22 and a plurality of apertures 32 adjacent theirrespective junctions, 34 and 36, with the central base piece, such thata line of uniformly-spaced coaxial connectors 20 can be housed adjaCentto and parallel with each junction. The central base piece defines acavity 22 and a plurality of apertures 32 adjacent each of thejunctions, 34 and 36, such that a line of uniformly-spaced coaxialconnectors 20 can be housed by the central base piece adjaCent to andparallel with each junction. Thus, at each junction of the central basepiece and an outer base piece there are two parallel lines of coaxialconnectors, one line on either side of the junction. preferably thespacing in each line of the two connector lines at a junction is equal,the number of connectors in each line is equal, and the two lines arelinearly skewed by an amount equal to half the distance between adjacentconnectors. Preferably the base plate 4 is made from aluminum, goldplated.

Referring to FIGS. 1 and 3-5, a contact leaf bank, generally designated40, is shown to comprise a sheet of resiliently flexible, electricallyconductive material in the form of a generally rectangular ground frame42 defining a plurality of uniformly-spaced, elongated, uniform,parallel slots 44 in which are disposed a corresponding plurality ofuniform, elongated strips of resiliently flexible, electricallyconductive material in the form of contact leaves 46, one contact leafcentrally disposed in each slot and held therein by laminates, 48 and50, which sandwich the ground frame and contact leaves therebetween. Thecontact leaves are coplanar with the ground frame except beyond a lineof divergence 52. An end portion of each contact leaf which divergesfrom the plane of the ground frame is a serrated-tip contact finger 54adapted to make electrical contact with the leads 56 of a device undertest 58. A portion of a top side 60 of the ground frame, the sideproximate and normal to the contact fingers 54, is scalloped orcrenelated with each merlon 62 aligned with one of the contact leavesand each crenel 64 aligned with one gap between contact leaves.Preferably both the ground frame and the contact leaves are made from aberylium and nickel or copper alloy which has good electricalconductivity and is resiliently flexible with high mechanical strengthand endurance, and both are gold-plated except for the serrated tips ofthe contact fingers 54 of the leaves which are rhodium-plated to makethem hard and wear resistant. The hardness of the contact fingers isadvantageous because in operation the fingers wipe against the deviceleads 56 and must penetrate surface contamination on the leads.

Referring again to FIGS. 1 and 3-5, the contact leaf bank 40 is shown inFIG. 4 to be in an unformed state, and is shown in the other figures tobe in a formed state. The formed state comprises a first uniform angularbend 66 of all contact fingers 54 along a line normal to the contactleaves 46 diverging the fingers from the plane of the contact leaf bank,a generally hook-shaped bend 68 of the ground frame 42 beginning along aline near and parallel to the bend 66 of the contact fingers anddivergent from the bend 66, and a second angular bend 70 of the groundframe crenelations inward toward the contact leaves. The bends are madeby deforming the items beyond their memory. The angular bend 66 at thecontact fingers is adapted to cause the contact fingers to impinge thedevice leads at an optimally advantageous angle. The hook-shaped bend 68is adapted to fold the ground frame away from the bent contact fingersand to conform the ground frame around an elongated rocker bar 72. Thebend 70 of the crenelations are adapted to cause the merlons 62 toproject at an optimally advantageous angle into a plurality of componentcells 74 to make electrical contact with an electrode of a component 76,e.g. a by-pass capacitor.

Referring to FIGS. 6-8, a rocker bar 72 is seen to comprise an elongatedbody 78 which defines a longitudinal slot 80 in which is disposed aplurality of component cells 74 only some of which are shown in FIG. 6.The component cells are defined by a first and second slat, 82 and 84,of insulating material which both run the length of the slot 80, andbetween said slats are a plurality of uniformly spaced partitions 86 ofinsulation material running transverse to the slot 80. Projectingaxially from opposite ends of the body 78 are a pair of dogs 88 by whichthe rocker bar is rotated toward and from the device 58 as will beexplained. Projecting radially from the body at opposite ends of saidbody are a pair of stops 90. The body also defines a pair of boltthrough holes 92 proximate opposite ends of said body. Optionally, anangle edge 94 around which the saddle of the hook-shaped bend 68 of theground frame is hooked is crenelated with the crenels 96 correspondingin number and aligning with the contact fingers 54. Recessing thefingers between the merlons thereof is a way of protecting them whilethe crenels permit visual inspection of the contact fingers. The body 78has two major sides, an inner side 98 which faces toward the contactfingers 54 and an outer side 100 which faces toward the crenels 62 of aformed contact leaf bank. The inner side 98 has projecting therefrom ateach end of the body 78 a pair of spaced shoulders 102A and 102B whichcrimp the contact leaf bank to hold it in place as will be explained.

Referring to FIGS. 1, 4 and 6, the contact leaf bank 40 at the cornersof side 60 defines a first pair of bolt holes 104, and intermediate side60 and its opposite side, the contact leaf bank defines a second pair ofbolt holes 106. When the formed contact leaf bank is hooked around therocker bar, these bolt holes 104 and 106 align with the rocker boltholes 92, and intermediate the bolt holes 104 and 106 are a pair of stopholes 108 through which project the rocker stops 90.

Referring to FIGS. 1, 3 and 5-7, the contact leaf bank 40 when it ishooked around the rocker bar 72 is clamped to the rocker bar by means ofa component cover bar 110 and a support bar 112. A pair of bolts 114extend through bolt holes 116 defined by the component cover bar, extendthrough the ground frame and rocker bolt holes 92, 104 and 106, and matewith threaded bores 118 defined by the support bar. The component coverbar bears against the outer side 100 of the rocker bar and visestherebetween the hooked ground plane. Interposed between the inner side98 of the rocker bar and the support bar is an elongated guard plate 120and a portion of the contact leaf bank 40. The guard plate 120 runs thelength of the rocker bar with one side abutting the support bar and theother side abutting the contact leaf bank, said other side having alongitudinal land 122 running the length of the plate, the width of theland 122 being suitably less than the gap between the rocker shoulders102A and 102B such that when the support bar is made to bear forcifullyagainst the guard plate by the bolts 114, the land 122 deforms andpushes the contact leaf bank into the rocker shoulder gaps therebycrimping the contact leaf bank. Intermediate the pairs of shoulders 120Aand 120B, the land also deforms and pushes a portion of the contact leafbank into a gap between the component cell slats 82 and 84 which projectfrom the inner side 98 coextensively with the shoulders 120A and 120B,respectively. Thus, the contact leaf bank is crimped laterally, alongthe land 122, between the rocker bar and the guard plate. The contactleaf bank, the guard plate, the rocker bar with component cells, thecomponent cover bar, and the support bar as assembled and bolted as inFIG. 3 are collectively called a rocker assembly which is generallydesignated 123.

The crimping of the contact leaf bank accomplishes several things.Firstly, it prevents movement of the contact leaf bank with respect tothe rocker bar. Secondly, the crimping causes the crimped portion of thecontact leaves to bow toward their respectively aligned component cells74 in order to make good electrical contact with an electrode of acomponent 76 therein. Thus, one electrode of a component in a cell is inelectrical contact with a crimped portion of a contact leaf 46 and theother electrode is in electrical contact with a ground frame merlon 62.If the ground frame is at electrical ground potential then thisarrangement creates a circuit between the contact leaf and a groundthrough the component. The important thing to note is that the circuitis created at the contact finger and therefore very near the device leadimpinged by the contact finger. Thus a device lead can be capacitivelybypassed or resistively terminated essentially right at the device lead.Such close proximity bypassing and termination is very important whentesting a device with high frequency signals having extremely shortwavelengths.

In its formed but unassembled state the ground frame is coplanar withthe contact leaves up to the bends 66 and beyond to the beginning ofbend 68. When the rocker assembly 123 is assembled, the saddle of thebend 68 is forced to seat on the crenelated angle ridge 94. The relativeposition of the angle ridge 94 to the shoulder 102A causes the groundframe 42 to bend away from the plane of the contact leaves 46 at theline of divergence 52 which is along the lateral crimp line of thecontact leaf bank 40. This divergence of the ground frame and the rockerbody 78 away from the contact fingers 54 (those portions of the contactleaves beyond the line of divergence 52) allows room for the fingers toflex during lead impingement.

A contact assembly 2 has two spaced-apart, parallel rocker assemblies123 with a base end portion of their respective contact leaf banks 40separately anchored in the junctions, 34 and 36, between the centralbase piece 8 and the outer base pieces, 10 and 12 respectively. The tworocker assemblies are hinged by the portions of their respectiveflexible contact leaf banks intermediate the base plate 4 and the rockerbar 72 and are oriented to reciprocatingly rotate oppositely to eachother such that the contact fingers 54 of the two rocker assemblies faceeach other. Thus, the device leads 56 on one side of a device 58 seatedon a device rail 128 interposed between the two rocker assemblies willbe impinged by the contact fingers of one rocker assembly while thedevice leads on the other side of the device will be impinged by thecontact fingers of the other rocker assembly.

Referring again to FIG. 1 and 3, it can be seen that the bent portion ofthe contact fingers 54 overhang a straight edge 124 of the guard plate120. (The righthand bank of contact fingers in FIG. 1 are notoverhanging the guard plate because the guard plate, rocker bar, andcontact leaf bank are shown spread apart as they would naturally be whenthe component cover bar 110 is unbolted from the support bar 112.) Inoperation, this edge limits the extent of flexing a contact tipundergoes when it impinges a device lead. As the rocker assembly 123 isrotated toward a line of device leads and the contact fingers arebrought to bear against with the device leads, the contact fingers willbe flexed backward by the leads causing the tips of the contact fingersto ride up the leads and thus wipe them. At a suitable point afterinitial contact, the straight edge comes into abutment with all thedevice leads and will thereafter prevent further backward flexing of thecontact leaves.

A pair of guard plate flanges 126 disposed at opposite ends of the guardplate project beyond the straight edge 124 and abut the rocker stops 90.The rocker bar 72 and the guard plate 120 are long enough to allow theirrespective stops and flanges to straddle the device. If no device ispresent when the rocker assembly is rotated, the guard plate flanges 126encounter a device guide rail 128, the guide rail upon which the deviceunder test is seated, and rotation of the rocker assembly toward themissing device is halted, thereby protecting the fingers 54 from contactwith the guide rail 128. After the rocker assembly is stopped,over-travel springs in the actuating mechanism (as will be explained)absorb any excess travel. The guide rail 128 is made of aluminum whichis covered by a dielectric surface finish such as obtained by hard coatanodizing. This prevents accidental shorting of device leads 56. The topsurface 128A, however, exposes bare metal to the body of device 58,preventing the accumulation of destructive electrostatic charges betweenthe devices and the contactor.

Referring to FIGS. 9-12, various views of a connector adaptor 130 areshown, FIGS. 9, 10 and 12 showing an unformed adaptor and FIG. 11showing a formed adaptor. In FIG. 12, the connector adaptor is shown tocomprise a sheet of resiliently flexible, electrically conductivematerial in the form of a generally rectangular ground frame 132defining a plurality of uniformly-spaced, elongated, uniform, parallelslots 134 in which are disposed a corresponding plurality of uniform,elongated strips of resiliently flexible, electrically conductivematerial in the form of contact leaves 136, one contact leaf centrallydisposed in each slot. FIGS. 9-11 show that the contact leaves 136 andthe ground frame 132 are secured in relation to each other by laminates138 and 140 which sandwich the ground frame and contact leavestherebetween. One long edge of the adaptor comprises a plurality ofserrated contact fingers: leaf fingers 142 and ground fingers 144. Theleaf fingers 142 are free (unlaminated) ends of the contact leaves 136,and the ground fingers 144 are unlaminated projections of the groundframe 132. An end portion of each contact leaf opposite its respectiveleaf finger 142 defines a signal lead solder hole 146 and radiallydisposed around said hole in a square pattern are four ground leadsolder holes 148 defined by the ground frame. Each set of four groundand one signal solder holes is adapted to match and align with the leadsof a coaxial connector 20 shown in FIG. 3. Each of the connectors 20 hasa signal lead 26 centered amongst four ground leads 24. As shown in FIG.3, the leads project through the holes and solder connections are madesuch that the four ground leads of each connector are in electricalcommunication with the ground frame 132 and the signal lead is inelectrical communication with a contact leaf 136. FIG. 9 shows a side ofthe connector adaptor 130 in which the laminate covers all except forthe holes themselves and the contact fingers. FIG. 10 shows an oppositeside of the adaptor where the laminate 138 defines sufficient clearancearound the holes for the solder connections. FIG. 12 shows a portion ofthe adaptor prior to lamination. Referring to FIG. 11, it can be seenthat the adaptor is bent along two lines parallel to and proximate thelong edge having the contact fingers 142 and 144. The two bends togetherform a generally S-shaped bend 150 when viewed from a short adaptoredge. The bends are made by deforming the material beyond its memory.

For proper testing, the number of contact leaves 46 in a contact leafbank 40 must at least match in number and spacing the device leads 56 onthe side of the bank. For each contact leaf there must be a coaxialconnector 20. However, the spacing of the contact leaves does not allowenough room for the required number of coaxial connectors to be in asingle line. That is the reason each junction, 34 and 36, between thecentral base piece 8 and an outer base piece, 10 or 12, has two lines ofconnectors linearly staggered. Interposed between the two lines ofconnectors at each junction is roughly a bottom third of the contactleaf bank with a base edge of the contact leaf bank being pinched by thejunction. Each connector adaptor 130 provides electrical communicationbetween a single line of connectors and the contact leaf bank. Thesolder hole sets (each set being one signal lead solder hole 146surrounded by four ground lead solder holes 148.) of each connectoradaptor are spaced to match and align with the leads of a single line ofcoaxial connectors. The adaptors solder onto the connector leads with aninsulation strip 152 interposed between the adaptors and the connectorbarrels. Since the leads of the connectors are generally parallel withthe plane of the portion of the contact leaf bank in a junction, theadaptors are disposed normal to the contact leaf bank with the S-shapedbends 150 toward the contact leaf bank. The opposing lines of connectorson either side of a junction are sufficiently close to the contact leafbank to cause the fingers, 142 and 144, of their respective adaptors tobe backwardly flexed so that they impinge the contact leaf bank withpressure and maintain that pressure. The adaptor for one connector lineimpinges the contact leaf bank on one side and the other adaptor for theother line of connectors impinges the contact leaf bank on the otherside. The signal fingers 142 of each adaptor are spaced to impinge ononly every other contact leaf 46 and the staggering of the connectorsensures that only one adaptor finger impinges each contact leaf. Theground fingers, however, from both opposing adaptors impinge on all ofthe ground straps between and outside of the contact leaves to minimizeground impedance.

The use of connector adaptors with resilient contact fingers whichimpinge the contact leaf bank with pressure is advantageous over asolder connection. With a solderless adaptation of the coaxialconnectors to the contact leaf bank, the contact leaf banks can bequickly and easily replaced in cases of wearout or accidental damagewithout any desoldering and soldering operations. Furthermore, a line ofcoaxial connectors 20 and the line's adaptor 130 with the insulationtherebetween can be assembled as a replaceable unit for likewise quickand easy replacement.

Referring to FIGS. 1 and 3, each contact leaf bank of a rocker assemblyis transversally crimped between a pair of skewed jaws 154A and 154Balong a line proximate and parallel to its respective junction, 34 or36, intermediate the junction and the rocker bar 72. There are two pairsof jaws, one pair associated with each junction, and the lines ofcrimping are generally coplanar with their respective junctions. Eachpair of jaws, 154A and 154B, are projections along an edge of a centralclamping plate 156 and an edge of an outer clamping plate, respectively,which are disposed in a shallow cavity 159 defined by the base plate.The central clamping plate 156 extends between the two opposing contactleaf banks, and has two such jawed edges on opposite sides bearingagainst the inboard sides of the contact leaf banks, and the outerclamping plates, 158A and 158B, each have a jawed edge bearing againstan outboard side of a coresponding contact leaf bank. The clampingplates are superimposed on the connector adaptors and the insulationstrips 152, and they define bores into which the leads of the connectorsextend. The clamping plates and their jaws are at least as long as thecontact leaf banks are wide. The crimping by the jaws cooperates withthe pinching of the contact leaf banks by the base pieces to stifflyhold the contact leaf banks therebetween for continuous and reliablecontact between the contact leaf bank and the fingers of the connectoradaptors. The line of crimping also provides a firm fulcrum line aboutwhich the rocker assemblies are hinged by their respective contact leafbanks.

Referring to FIGS. 13-15 a bridge, generally designated 160, is seen tocomprise a rectangular housing 162, a cover 164, and two oppositelyreciProcating rocker actuating mechanisms, generally designated 166. Thebridge 160 is superimposed upon the contact assembly 2 such that thehousing 162 abuts a top margin of the contact assembly base plate 4 andis bolted thereto by means of bolts (not shown) extending throughcontact assembly counter-sunk bolt holes 168 (see FIGS. 1 and 2) andbridge bolt holes 170. When the bridge is superimposed upon the contactassembly, the opposing rocker assemblies 123 project through gaps 172Aand 172B between the device rail 128 and the actuating mechanisms 166,and straddle the device guide rail.

The housing 162 is basically a rectangular frame having long framemembers 174A and 174B and short frame members 176A and 176B made frommaterial characterized by mechanical strength and high thermalinsulation. The contactor of this invention is used to test devices atvariable temperature, so in operation the contactor is mounted in acontrolled-environment chamber wall aperture (not shown) with one sideof the wall being at variable temperature extremes and the other sidebeing at a stable temperature favorable to testor electronics. Afunction of the housing is to provide a thermal barrier to protect thebase plate from the varying and extreme temperatures. To further enhanceits thermal insulation characteristics, the housing frame members definea plurality of air trapping cavities 178A and 178B on the sides facingthe base plate 4 and the cover 164. Air having a very low thermalcoefficient helps to minimize heat transfer from the cover to the baseplate. Extending inward along the base plate side of the housing are apair of integral flanges 180A and 180B to provide further thermalinsulation. When the bridge is superimposed onto the contact assembly,the extents of the flanges meet the extents of the contact assemblyouter clamping plates 158A and 158B which, together with the centralclamping plate 156, provide a comprehensive thermal barrier for the baseplate. The housing also has four uniform and parallel, integral guiderails 182 projecting inward from the long frame members at the framecorners.

Referring to FIG. 13, a conventional contactor drive mechanism is seento comprise a solenoid 184 powered by an energy source 186 andcontrolled by a switching means 188. The solenoid acts against a biasingspring 189. The shaft 190 of the solenoid is adapted to engage a pair ofcranks 192A and 192B to reciprocatingly turn the cranks in oppositedirections through a suitable angle. Affixed to each crank is a driveshaft 194 to which is affixed a drive dog 196. The drive shafts rotatecoaxially with the cranks, and the drive dogs are moved through an arcas indicated by the arrows.

Referring to FIG. 14-16, an actuating mechanism 166 is seen to comprisea leader bar 198 with two integral sliders 200A and 200B at oppositeends which slidably travel on the housing guide rails 182, a spacedfollower bar 202 parallel to the leader bar with two integral sliders204A and 204B at opposite ends which slidably travel on the housingguide rails 182, a spring means comprising a pair of coiled springs 206linking the two bars, a pair of hook-like links 208 affixed to oppositeends of the follower bar and adapted to hook over the rocker dogs 88 atopposite ends of a rocker assembly 123 when the bridge is superimposedupon the contact assembly 2, a drive dog gap 210 between the leader andfollower bars, and bearing inserts 212A and 212B between the drive dogand the bars. In FIG. 16 the drive dogs 196 are shown in phantom in thegaps 210, and the directions of drive dog movement are shown by thearrows beneath them.

In operation, when the drive dogs are moving inboard, that is, towardthe center of the bridge, they forcibly press against the bearinginserts 212A of the leader bars 198 moving said bars with them. Thefollower bars 202 because they are linked to the leader bars by thecoiled springs 206 will follow bringing the rocker dog links with them.The rocker dog links will force the rocker assemblies 123 to rotateinboard toward the device rail 128, and if a device is seated on therail, the contact fingers 54 at some point will impinge the device leadsand begin flexing backward and wiping the leads. At a further point theguard plates will meet the device leads and will, due to the resistanceof the leads, stop any further inboard rotation of the rockerassemblies. Even if the resistance of the leads does not stop theinboard rotation, the guard plate flanges 126 will meet the device railand stop said rotation before the contact fingers can be shorted ordamaged. If the drive dogs continue their inboard course after therocker assemblies have been stopped, the over- travel will be taken upby the coiled springs, that is, if the leader bars continue to be forcedinboard while the follower bars are stopped by the guard plates, thecoiled springs will expand to allow the drive dogs to over-travel.Limits to the over-travel are provided by a shoulder 214 (see FIG. 3) ofeach outer clamping plate 158 which presents a stop in the path of itscorresponding leader bar.

Referring to FIGS. 17-19, a conventional contactor is shown to comprisea plurality of individually assembled contact fingers 250 disposed in atwo layered base 252 and actuated by a reciprocating slide member 254.It should be noted that the conventional contactors are hand-assembled,that is, each individual contact finger must be assembled andhand-placed into its base.

The foregoing description and drawings were given for illustrativepurposes only, it being understood that the invention is not limited tothe embodiments disclosed, but is intended to embrace any and allalternatives, equivalents, modifications and rearrangements of elementsfalling within the scope of the invention as defined by the followingclaims.

I claim:
 1. A contact leaf bank for an electrical contactorcomprising:(a) a uniform sheet of electrically conductive material, (b)a plurality of elongated leaves of resiliently flexible electricallyconductive material each having an end portion adapted to be a contactfinger, (c) a corresponding plurality of uniformly-spaced, elongated,parallel slots defined by the sheet in which the leaves are uniformlyand centrally disposed, one leaf in each slot, the leaves beinggenerally coplanar with the sheet except for a line of divergencebetween the sheet and the leaves proximate the contact fingers, and (d)means securing the strips and the sheet in relation to each other. 2.The contact leaf bank of claim 1 wherein the means securing the leavesand the sheet in relation to each other comprises lamination means. 3.The contact leaf bank of claim 1 wherein the dimensions of the leaves,the slots and the spaces between the slots give each leaf an electricalcharacteristic impedance, with respect to the sheet, of a coplanar striptransmission line.
 4. The contact leaf bank of claim 2 wherein thedimensions of the leaves, the slots and the spaces between the slotsgive each leaf an electrical characteristic impedance, with respect tothe sheet, of a coplanar strip transmission line.
 5. The contact leafbank of claim 3 wherein the electrical characteristic impedance of theleaves are uniform and substantially match the impedance of a coaxialtransmission line.
 6. The contact leaf bank of claim 4 wherein theelectrical characteristic impedance of the leaves are uniform andsubstantially match the impedance of a coaxial transmission line.
 7. Thecontact leaf bank of claim 1 or 2 wherein the ends of the contactfingers are rhodium plated for additional hardness.
 8. The contact leafbank of claim 3 or 4 wherein the ends of the contact fingers are rhodiumplated for additional hardness.